DOCSLIB.ORG

The Biology of Asterias Rubens L. Ii

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Biology of Asterias Rubens L. Ii 619 THE BIOLOGY OF ASTERIAS RUBENS L. II. PARASITIZATION OF THE GONADS BY THE CILIATE ORCHITOPHRYA STELLARUM CBPEDE By H. G. Vevers, M.A., D.Phil. Zoologist at the Plymouth Laboratory (Plate I) CONTENTS PAGE Introduction . 619 Distribution of the Parasite off Plymouth 619 Distribution of the Parasite within the Host . 621 Effect of the Parasite on the Testes of Asterias rubens 622 Discussion. 623 Summary 624 References. 624 INTRODUCTION The astomatous holotrich ciliate, Orchitophrya stellarum, was originally described and named by Cepede (I907a, b), who found it in the gonads of only three males out of a total of over 6000 Asterias rubens of both sexes. These starfishes were taken by him from the Boulogne and Wimereux area. There was no trace of the parasite in any ovaries, but he noticed that it caused a partial and direct castration of its male host. Orchitophrya was' found by Piatt (1935) in the testes of Asterias forbesi in Long Island Sound, where Burrows (1936) observed that the percentage of parasitized males varied from I to 20% according to the locality. Burrows also found that a small number of the female starfishes (about I %) were infected. Smith (1936) recorded the parasite in the ovaries of about 25 % of the femalesof A. vulgarisfrom oyster beds in Malpeque Bay, Prince Edward Island. Eggs taken from these infected ovaries appeared normal and were fertilizable. I am indebted to Mr Y. R. Tripathi for assistancein the originalidentification of the parasite, and to Dr J. S. Alexandrowicz for making the photomicrographs. DISTRIBUTION OF THE PARASITE OFF PLYMOUTH During the years 1946-50 large numbers of A. rubens have been trawled from different localities in the Plymouth area. In the course of investigations on the reproductive cycle in these localized populations, smears have been taken 620 H. G.VEVERS from the gonads of each starfish and transverse sections cut of a number of selected gonads. In March 1947 trawling was commenced on the Outer Grounds, to the south and south-west of Eddystone. The differencesbetween the starfishfrom this area and those from the more northerly Rame-Eddystone Grounds have already been described (Vevers, 1949). Orchitophryastellarum was found in a varying percentage of the males from all the six trawl hauls taken in spring 1947 on the Outer Grounds. In the earlymonths of the years 1948,1949and 1950the parasitewas again found in malestarfishesfrom these Grounds and also in a population of Asteriasrubenstrawled from Asia Shoal, Plymouth Sound. The parasite has never been found in starfishes from the geographicallyintermediateRame-Eddystone Grounds. The significanceofthis TABLE I. ANALYSIS OF PARASITE OCCURRENCES IN STARFISH FROM HAULS FROM OUTER GROUNDS AND PLYMOUTH SOUND Approx. percentage Total in Total No. of males of males Date haul males parasitized parasitized (a) Outer Grounds 20. iii.47 33 12 3 25 9.iv.47 29 II '3 27 17. iv. 47 44 17 4 24 18. iv. 47 50 25 7 28 25. iv. 47 175 '66 16 24 23.v.47 57 17 2 12 IS. i. 48 29 IS I 7 12. iii.48 38 IS I 7 14. iv. 48 103 50 6 12 13. v. 48 231 87 I I 10. ii.49 63 26 2 8 15. iii.49 46 17 I 6 14.ii.50 41 23 2 9 9. iii. 50 79 32 3 10 (b)Plymouth Sound (Asia Shoal) 16. iv. 48 100 52 3 6 20. iv. 49 .25 10 I 10 10. iii. 50 80 37 I 3 distribution will be discussedlater. Table I gives a synopsisof the occurrences of Orchitophryastellarumin Asteriasrubensfrom the Plymouth area. The occurrence of the parasite is strictly seasonal. It has only been found near Plymouth during January to May (inclusive) when the host's testes are either ripe or nearly ripe. Smith (1936)and Burrows (1936)both record it as occurring during' summer'. The absolute number of parasitized starfishes caught in anyone haul is necessarily small and so it is difficultto obtain a figure representing the true percentage of malesinfected. However, the data given in Table I show clearly that the percentageinfected was much greater in 1947than in any of the three succeeding years. The catches taken from the Outer Grounds in March and April 1947 gave very constant percentages of infected males. A month later BIOLOGY OF ASTER/AS 621 (23 May 1947)the percentage infected had dropped to half; probably because most of the males had spawnedin the meantime, leavingfewer ripening testes available for the parasites. In January-April 1948 the percentage infected was, on the average, 10, and again there was a sharp drop in percentage to less than 2 in May. There were only two infected catches in 1949 from the Outer Grounds, one in February and one in March, and the percentage with parasites was less than 10. The same was found in the two catches for 195°. In the Plymouth Sound starfish population Orchitophryahas been found only in small numbers in one catch in each of the years 1948, 1949 and 195°. The percentage of males infected was proportionately much greater in the size classes10.0-19.9 em. than in the sizeclasses5.0-9.9 cm. and 20.0-25.9 cm. (Table II). In the lower-size classes(5.0-9.9 em.) the scarcity of parasitized individuals is understandable, since some, at least, of these starfishes were definitely juvenile with testes which shOwedno signs of ripening at the time of observation. TABLE II. SIZE DISTRIBUTIONOF INFECTEDMALES IN THE POPULATION(OUTER GROUNDS) Infected Percentage Size class in cm. Total males males infected 5.00-9.9 35 2 6 10.0-14.9 162 29 18 15.0-19.9 181 19 II 20.0-25.9 35 I 3 The very low percentage of infections in the highest size classes (20.0-25.9 cm.) suggests that there may be a certain resistance to the parasites with increased host size. There is, however, no direct evidence for this inter- pretation. DISTRIBUTION OF THE PARASITE WITHIN THE HOST Burrows (1936) noted variation in. the amount of parasites within the indi- vidual, including cases where some gonads were parasitized and others were normal. Similar conditions were found in the present investigation, thus in starfish 3076 (16 April 1948) there was a very heavy infection of the testes in arm II/interradius 2/3, while all the rest of the testes showed mobile spermatozoa and no parasites. In starfish 3°87 (16 April 1948) there were medium infections in two testes in non-contiguous arms and no parasites in the other eight gonads. At the time these starfishes were caught, in mid- April, most of the starfishes on the Outer Grounds were ripe, but few had spawned. In the previous year larger catches of.starfishes were made, and among these were a few in which ripe, spawned and parasitized testes were 622 H. G.VEVERS found in the same animal. Thus in starfish 998 (23 May 1947)the condition of the gonads was: . Arm lnterradius Condition of gonad I sir Spawned, re-ripening r/2 Spawned II Arm missing III 2/3 Spawned 3/4 Mobile sperm distally, rest spawned IV 3/4 Few parasites 4/5 Few parasites V 4/5 Mobile sperm distally, rest spawned sir Spawned There is no doubt that the main centre of infection is in the testes, although the parasites can sometimes be found in other organs. In starfish 640, for instance, Orchitophrya was found in the gut and coelomic fluid as well as in the testes, but not in the digestive coeca or tube feet. These are probably chance infections from lesions in the testis and are not considered to be of any importance. EFFECT OF THE PARASITE ON THE TESTES OF ASTERIAS RUBENS Cepede (1910) gives a good description of the morphology and life cycle of the parasite, and he noted that it caused partial or direct castration of the host. His material was very limited and neither he nor subsequent workers have recorded the histological changes which occur in testes infected with Orchito- phrya. With the large number of infected males available from the Plymouth . grounds, it has now been possible to obtain further information on this subject. In the early stages of infection the testes still have well developed sper- matogonial ridges, with numerous spermatocytes and spermatids filling the lumen of each tubule. As the parasites increase in number, the sexual pro- ducts in the lumen disappear and a transverse section then shows that each tubule has distinct spermatogonial ridges and its lumen is filled with parasites. The ridges become progressively smaller and the parasites increasingly crowded (PI. I, fig. I). The nutrient medium in which the parasites are living is that of the ripening germ cells, and as the latter disappear so does the food supply of the parasites. When this happens the parasites start to decrease in numbers and the gonad tubules show only a very thin layer of genital epithelium (PI. I, figs. 2 and 4). In this stage the connective tissue sheath begins to thicken, probably due to a shrinking of the whole tubule, as it becomes less distended with parasites. Finally, very few parasites are left in the tubule lumina, there is little or no trace of genital epithelium and all that remains are the thick shrunken sheaths of the original testis tubules (PI. I, fig. 3). BIOLOGY OF ASTER/AS 623 DISCUSSION The spread of the parasite would appear to be greater in starfish populations which are relatively crowded, for the largest percentages of infected males occurred on the Outer Grounds in 1947.
Load more

Recommended publications
  • The Ciliate Orchitophrya Stellarum Viewed As a Facultative Parasite of Asteriid Sea Stars
    Cah. Biol. Mar. (2007) 48 : 9-16 The ciliate Orchitophrya stellarum viewed as a facultative parasite of asteriid sea stars William B. STICKLE1, Eugene N. KOZLOFF2* and Margaret C. HENK1 (1) Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, 70803-1715, USA (2) Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, 98250, USA *Corresponding author: Fax: (1) 206 543 1273. E-mail: [email protected] Abstract: Orchitophrya stellarum Cépède, 1907 is a ciliate that consumes sperm in the testes of male asteriid sea stars in the Pacific and North Atlantic oceans. Previous studies have reported its presence in smears and sections of testes, and we have also observed it in the spawn. This organism is easily cultured in seawater containing bacteria nourished by yeast extract or tissues from various marine invertebrates and the domestic chicken. During adaptation to culture conditions, the ciliates become smaller, the number of kineties is reduced, and the buccal cavity is shifted farther away from the anterior end. These changes are reversed if the ciliates are fed sperm of asteriid sea stars. Orchitophrya stellarum is therefore consi- dered to be a facultative parasite that can live indefinitely in situations where it can feed on bacteria and tissue detritus. It probably enters the testes of reproductively mature male sea stars by way of the gonopores. Resumé : Le cilié Orcitophyra stellarum vu comme un parasite possible des étoiles de mer astériide. Le cilié Orchitophrya stellarum Cépède, 1907, parfois trouvé dans les étoiles de mer asterides mâles dans les océans Pacifique et Atlantique Nord, se nourrit de spermatozoïdes.
    [Show full text]
  • Final Study Report
    OCS Study BOEMRE 2010-05 Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities Adjacent to OCS Activities – Final report (2007-2010) Final Technical Summary Final Study Report U.S. Department of the Interior BOEMRE Bureau of Ocean Energy Management, Regulation and Enforcement Pacific OCS Region OCS Study BOEMRE 2010-05 Multi-Agency Rocky Intertidal Network (MARINe) Study of Rocky Intertidal Communities Adjacent to OCS Activities – Final report (2007-2010) Final Technical Summary Final Study Report Project Manager Peter T. Raimondi Principal Investigators Richard Ambrose Jack Engle Steve Murray Jayson Smith Study design, oversight, and funding were provided by the U.S. Department of the Interior, Bureau of Ocean Energy Management, Regulation and Enforcement, Environmental Studies Program, Washington, DC under Agreement Number M07AC12503 by Center for Ocean Health Long Marine Laboratory University of California Santa Cruz, CA 93106 Disclaimer This report has been reviewed by the Pacific Outer Continental Shelf Region, Bureau of Ocean Energy Management, Regulation and Enforcement, U.S. Department of the Interior and approved for publication. The opinions, findings, conclusions, and recommendations in this report are those of the authors, and do not necessarily reflect the views and policies of the Bureau of Ocean Energy Management, Regulation and Enforcement. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use. This report has not been edited for conformity with Bureau of Ocean Energy Management, Regulation and Enforcement editorial standards. Availability of Report Extra copies of the report may be obtained from: U.S. Dept. of the Interior Bureau of Ocean Energy Management, Regulation and Enforcement Pacific OCS Region 770 Paseo Camarillo Camarillo, CA 93010 Phone: 805-389-7621 Suggested Citation The suggested citation for this report is: Raimondi, P.T.
    [Show full text]
  • Orchitophrya Stellarum (Ciliophora)
    DISEASES OF AQUATIC ORGANISMS Vol. 10: 71-73, 1991 Published March 8 l Dis. aquat. Org. I NOTE Castration and mortality in Pisaster ochraceus parasitized by Orchitophrya stellarum (Ciliophora) B. J. eighto on', J. D. G. Boom1, C. ~ouland*,E. B. Hartwick', M. J. Smith1 ' Department of Biological Sciences, Simon Fraser University, Burnaby. British Columbia, Canada V5A IS6 Department of Biology, University of Victoria, Victoria. British Columbia, Canada V8W 2Y2 ABSTRACT: A swey of the sex-ratio and gonadal index of consequences in P. ochraceus and the occurrence of sea stars Pisaster ohraceus (Brandt, 1835) at 2 sites on the the ciliate Orchitophrya stellarum in a Pacific sea star. southern coast of British Columbia, Canada, revealed an Methods and materials. Specimens of Pisaster e~izooticdisease affectina- the testes. The disease reduced the proportion of males and their reproductive potential in the ochraceus were collected by SCUBA at a depth of 0 to ~owulationsstudied. Examination of diseased testes revealed 10 m in Indian Arm during the years 1980, 1981, 1985 the presence of a parasitic ciliate, Orchitophrya stellarum and 1987 to 1989, and from Bowen Island during 1981 Cepede, 1907, that has not previously been reported from the and 1987 to 1989, both sites located near Vancouver, Pacific Ocean. The more virulent nature of the parasite in P. ochraceus, as compared with its Atlantic and Mediterra- British Columbia. The sex of the sea stars was deter- nean hosts, may indicate the recent introduction of the para- mined by examining a fresh gonad smear under a site into the Pacific. standard compound microscope (magnification = 100~)and the sex-ratio of males to females was The only ciliate known to parasitize echinoderms is recorded.
    [Show full text]
  • Glossary for the Echinodermata
    February 2011 Christina Ball ©RBCM Phil Lambert GLOSSARY FOR THE ECHINODERMATA OVERVIEW The echinoderms are a globally distributed and morphologically diverse group of invertebrates whose history dates back 500 million years (Lambert 1997; Lambert 2000; Lambert and Austin 2007; Pearse et al. 2007). The group includes the sea stars (Asteroidea), sea cucumbers (Holothuroidea), sea lilies and feather stars (Crinoidea), the sea urchins, heart urchins and sand dollars (Echinoidea) and the brittle stars (Ophiuroidea). In some areas the group comprises up to 95% of the megafaunal biomass (Miller and Pawson 1990). Today some 13,000 species occur around the world (Pearse et al. 2007). Of those 13,000 species 194 are known to occur in British Columbia (Lambert and Boutillier, in press). The echinoderms are a group of almost exclusively marine organisms with the few exceptions living in brackish water (Brusca and Brusca 1990). Almost all of the echinoderms are benthic, meaning that they live on or in the substrate. There are a few exceptions to this rule. For example several holothuroids (sea cucumbers) are capable of swimming, sometimes hundreds of meters above the sea floor (Miller and Pawson 1990). One species of holothuroid, Rynkatorpa pawsoni, lives as a commensal with a deep-sea angler fish (Gigantactis macronema) (Martin 1969). While the echinoderms are a diverse group, they do share four unique features that define the group. These are pentaradial symmetry, an endoskeleton made up of ossicles, a water vascular system and mutable collagenous tissue. While larval echinoderms are bilaterally symmetrical the adults are pentaradially symmetrical (Brusca and Brusca 1990). All echinoderms have an endoskeleton made of calcareous ossicles (figure 1).
    [Show full text]
  • Full Text in Pdf Format
    DISEASES OF AQUATIC ORGANISMS Vol. 40: 79-83,2000 Published February 24 Dis Aquat Org l l NOTE Conservation of sequence in the internal transcribed spacers and 5.8s ribosomal RNA among geographically separated isolates of parasitic scuticociliates (Ciliophora, Orchitophryidae)' C. L. Goggin**,N. E. Murphy Centre for Research on Introduced Marine Pests (CRIMP). CSIRO Marine Research, GPO Box 1538. Hobart Tasmania 7001. Australia ABSTRACT: Nucleotide sequence from the internal tran- plement classical morphological taxonomy. In particu- scribed spacers (ITS1 and ITS2) and the 5.8s gene from the lar, the internal transcribed spacers (ITS1 and ITS2) in r~bosomalRNA gene cluster of isolates of the scuticociliate the nbosomal RNA (rRNA) gene cluster have been Orchitophrya stellarum from 4 asteroid hosts were compared. Surprisingly, these data (495 bp) were identical for 0. stel- used to discriminate the alveolates which comprise the larum isolated from the testes of Astenas amurensis from apicomplexans (Cai et al. 1992, Goggin 1994, Schlot- Japan; Pisaster ochraceus from British Columbia, Canada; terer et al. 1994, Homan et al. 1997), dinoflagellates Asterias rubens from The Netherlands; and Astenas vulgaris (Hudson & Adlard 1996) and ciliates (Diggles & Adlard from Prince Edward Island, Canada. These sequence data were compared to those from 3 scuticociliates which para- 1997). We investigated the utility of this region to dis- sitise crustaceans: Mesanophrys pugettensis, M. chesapeak- criminate orchitophryid scuticociliates which are geo- ensis and Anophryoides haemophila. No difference was graphically separated. found in this region between the nucleotide sequence of In particular, we chose the parasitic scuticociliate M pugettensis and M. chesapeakensis The sequence of Orchitophrya stellarum which was first described Mesanophrys spp.
    [Show full text]
  • Benthic Invertebrates of the Eastern Bering Sea: a Synopsis of the Life History and Ecology of the Sea Star Asterias Amurensis
    NOAA Technical Memorandum NMFS-AFSC-273 Benthic Invertebrates of the Eastern Bering Sea: A Synopsis of the Life History and Ecology of the Sea Star Asterias amurensis by K. R. Smith and C. E. Armistead U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Alaska Fisheries Science Center April 2014 NOAA Technical Memorandum NMFS The National Marine Fisheries Service's Alaska Fisheries Science Center uses the NOAA Technical Memorandum series to issue informal scientific and technical publications when complete formal review and editorial processing are not appropriate or feasible. Documents within this series reflect sound professional work and may be referenced in the formal scientific and technical literature. The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries Science Center continues the NMFS-F/NWC series established in 1970 by the Northwest Fisheries Center. The NMFS-NWFSC series is currently used by the Northwest Fisheries Science Center. This document should be cited as follows: Smith, K. R., and C. E. Armistead. 2014. Benthic invertebrates of the eastern Bering Sea: A synopsis of the life history and ecology of the sea star Asterias amurensis. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-273, 60 p. Document available: http://www.afsc.noaa.gov/Publications/AFSC-TM/NOAA-TM-AFSC-273.pdf Reference in this document to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. Photo: J. Haaga (NMFS-NOAA-AFSC). NOAA Technical Memorandum NMFS-AFSC-273 Benthic Invertebrates of the Eastern Bering Sea: A Synopsis of the Life History and Ecology of the Sea Star Asterias amurensis by K.
    [Show full text]
  • Mytilus Edulis Beds on Sublittoral Sediment
    MarLIN Marine Information Network Information on the species and habitats around the coasts and sea of the British Isles Mytilus edulis beds on sublittoral sediment MarLIN – Marine Life Information Network Marine Evidence–based Sensitivity Assessment (MarESA) Review Dr Heidi Tillin & Kathryn Mainwaring 2016-02-09 A report from: The Marine Life Information Network, Marine Biological Association of the United Kingdom. Please note. This MarESA report is a dated version of the online review. Please refer to the website for the most up-to-date version [https://www.marlin.ac.uk/habitats/detail/36]. All terms and the MarESA methodology are outlined on the website (https://www.marlin.ac.uk) This review can be cited as: Tillin, H.M. & Mainwaring, K., 2016. [Mytilus edulis] beds on sublittoral sediment. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on- line]. Plymouth: Marine Biological Association of the United Kingdom. DOI https://dx.doi.org/10.17031/marlinhab.36.1 The information (TEXT ONLY) provided by the Marine Life Information Network (MarLIN) is licensed under a Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales License. Note that images and other media featured on this page are each governed by their own terms and conditions and they may or may not be available for reuse. Permissions beyond the scope of this license are available here. Based on a work at www.marlin.ac.uk (page left blank) Date: 2016-02-09 Mytilus edulis beds on sublittoral sediment - Marine Life Information Network Mytilus edulis beds on sublittoral sediment Photographer: Keith Hiscock Copyright: Dr Keith Hiscock 17-09-2018 Biotope distribution data provided by EMODnet Seabed Habitats (www.emodnet-seabedhabitats.eu) Researched by Dr Heidi Tillin & Kathryn Mainwaring Refereed by This information is not refereed.
    [Show full text]
  • Exploring the Pathology of an Epidermal Disease Affecting a Circum-Antarctic Sea Star
    www.nature.com/scientificreports Correction: Author Correction OPEN Exploring the pathology of an epidermal disease afecting a circum-Antarctic sea star Received: 31 January 2018 Laura Núñez-Pons 1,2, Thierry M. Work 3, Carlos Angulo-Preckler 4, Juan Moles 5 & Accepted: 16 July 2018 Conxita Avila 4 Published: xx xx xxxx Over the past decade, unusual mortality outbreaks have decimated echinoderm populations over broad geographic regions, raising awareness globally of the importance of investigating such events. Echinoderms are key components of marine benthos for top-down and bottom-up regulations of plants and animals; population declines of these individuals can have signifcant ecosystem-wide efects. Here we describe the frst case study of an outbreak afecting Antarctic echinoderms and consisting of an ulcerative epidermal disease afecting ~10% of the population of the keystone asteroid predator Odontaster validus at Deception Island, Antarctica. This event was frst detected in the Austral summer 2012–2013, coinciding with unprecedented high seawater temperatures and increased seismicity. Histological analyses revealed epidermal ulceration, infammation, and necrosis in diseased animals. Bacterial and fungal alpha diversity was consistently lower and of diferent composition in lesioned versus unafected tissues (32.87% and 16.94% shared bacterial and fungal operational taxonomic units OTUs respectively). The microbiome of healthy stars was more consistent across individuals than in diseased specimens suggesting microbial dysbiosis, especially in the lesion fronts. Because these microbes were not associated with tissue damage at the microscopic level, their contribution to the development of epidermal lesions remains unclear. Our study reveals that disease events are reaching echinoderms as far as the polar regions thereby highlighting the need to develop a greater understanding of the microbiology and physiology of marine diseases and ecosystems health, especially in the era of global warming.
    [Show full text]
  • Emerging Infectious Disease in Sea Stars: Castrating Ciliate Parasites in Patiria Miniata
    Vol. 81: 173–176, 2008 DISEASES OF AQUATIC ORGANISMS Published August 27 doi: 10.3354/dao01949 Dis Aquat Org NOTE Emerging infectious disease in sea stars: castrating ciliate parasites in Patiria miniata J. Sunday*, L. Raeburn, M. W. Hart Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada ABSTRACT: Orchitophrya stellarum is a holotrich ciliate that facultatively parasitizes and castrates male asteriid sea stars. We discovered a morphologically similar ciliate in testes of an asterinid sea star, the northeastern Pacific bat star Patiria miniata (Brandt, 1835). This parasite may represent a threat to Canadian populations of this iconic sea star. Confirmation that the parasite is O. stellarum would indicate a considerable host range expansion, and suggest that O. stellarum is a generalist sea star pathogen. KEY WORDS: Scuticociliate · Asterias amurensis · Biocontrol · Sperm Resale or republication not permitted without written consent of the publisher INTRODUCTION consequences for ecologically important sea stars. In North America, recently described pathogenic infec- The spread of infectious pathogens may be tions of asteriid hosts (Leighton et al. 1991, Stickle et enhanced by direct human dispersal or through indi- al. 2001, 2007a,b), including the keystone predator rect facilitation such as climate change (Dobson & Pisaster ochraceus Brandt, 1835, have been attributed Foufopoulos 2001). Such emergent diseases have to inadvertent anthropogenic introduction of O. stel- important implications for natural and managed larum; some P. ochraceus populations in Canada have ecosystems (Krkosek et al. 2007). When emergent dis- been devastated. Deliberate introduction of O. stel- eases interact with invasive host species, pathogens larum into Tasmania has been proposed as a biocontrol may limit the spread of these hosts or merely use them measure to eradicate invasive populations of A.
    [Show full text]
  • D080p037.Pdf
    Vol. 80: 37–43, 2008 DISEASES OF AQUATIC ORGANISMS Published June 19 doi: 10.3354/dao01917 Dis Aquat Org Association and distribution of the ciliate Orchitophrya stellarum with asteriid sea stars on the west coast of North America William B. Stickle1,*, Eugene N. Kozloff 2 1Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803-1715, USA 2Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington 98250, USA ABSTRACT: The association of the scuticociliate Orchitophrya stellarum with 3 species of asteriid sea stars from the west coast of North America was studied by flushing the gonopore region with sea- water and spawning the sea stars, along a latitudinal gradient of 2549 km between Pigeon Point, California, and Kodiak, Alaska. Asterias forbesii and A. rubens from the Isles of Shoals, New Hamp- shire (east coast), were also sampled. The ciliate was found on the aboral surface of both sexes of reproductively ripe Evasterias troschelii, Leptasterias spp., and Pisaster ochraceus with a maximum intensity of association occurring at Cape Arago, Oregon, and Clallum Bay and Manchester Dock, Washington. A survey of gonad smears and hematoxylin and eosin-stained sections indicated that the ciliate was only present in males. Spring-spawning E. troschelii and P. ochraceus are more negatively impacted by the ciliate than are winter-spawning Leptasterias spp. as judged by a skewed sex ratio and sex size differences, which may be associated with seasonal differences in water temperature affecting the growth rate of O. stellarum. The external morphology of O. stellarum appears to be similar throughout the geographical range surveyed.
    [Show full text]
  • Echinodermata)
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by PubMed Central Review Global Diversity and Phylogeny of the Asteroidea (Echinodermata) Christopher L. Mah1,2*, Daniel B. Blake3 1 Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, United States of America, 2 Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of Ameica, 3 Department of Geology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America Asteroids are dorsoventraly flattened with five to 50 rays Abstract: Members of the Asteroidea (phylum Echinoder- projecting from a central disk. Each arm possesses a series of mata), popularly known as starfish or sea stars, are paired J-shaped ambulacral ossicles that occur along each arm ecologically important and diverse members of marine radius. Tube feet emerge from pores present between ambulacral ecosystems in all of the world’s oceans. We present a ossicles into a large ventrally facing open groove. These grooves all comprehensive overview of diversity and phylogeny as converge on the mouth, present on the bottom-facing side of the they have figured into the evolution of the Asteroidea from disk. Although supported as members of the asteroid lineage, Paleozoic to the living fauna. Living post-Paleozoic asteroids, the Neoasteroidea, are morphologically separate concentricycloids (represented by the monotypic Xyloplax) show a from those in the Paleozoic. Early Paleozoic asteroid faunas highly divergent morphology that has suggested separation of were diverse and displayed morphology that foreshad- Xyloplax from the other Asteroidea. This includes unpaired, non- owed later living taxa.
    [Show full text]
  • The Echinoderm Newsletter
    THE ECHINODERM NEWSLETTER Number 25. 2000 Editor: Cynthia Ahearn smithsonian ~stitution National Museum of Natural History Room W-318, Mail Stop 163 Washington D.C. 20560-0163 U.S.A. **** E-MAJ:L **** ahearn. cynthia@nmnh. si •edu **** Distributed by: David Pawson smithsonian Institution National Museum of Natural History Room W-323, Mail Stop 163 Washington D.C. 20560-0163 U.S.A. The newsletter contains info:rmation concerning meetings and conferences, publications of interest to echinoderm biologists, titles of theses on echinoderms, and research interests, and addresses of echinoderm biologists. Individuals who desire to receive the newsletter should send their name, address and research interests to the editor. The newsletter is not intended to be a part of the scientific literatUre and should not be cited, abstracted, or reprinted as a published document. Sladen 1889 http://www.DmDh.si.edu/iz/echinoder.m •.. TABLE OF CONTENTS Echinoderm Specialists Addresses; (p-); Fax (f-); e-mail numbers 4 Current Research 47 Echinoderm Specialists 'Keyword' List 77 Echinoderm Web Pages 86 Theses and Dissertations 91 Announcements Echinoderm-L (Echinoderm mailing list) 96 J. Douglas McKenzie (Integrin Advanced Biosystems Ltd) 97 Phylum Echinodermata is now on the Tree of Life 97 New mailing list on BIODIVERSITY is born 98 George Washington University Post-Doctoral position 98 Book Mailing Announcement from Peter Jell 99 Sea Urchin (Tripneustes gratilla) Research Project 99 Conference Announcements 4th North American Echinoderm Conference 101 6th European Conference on Echinoderms 103 Advanced Workshop in Honour of Eizo Nakano, Sea Urchin Aquacul ture 103 5th Congress on Marine Sciences (Marcuba '2000) 106 Information Requests 108 Ailsa's Section Echinoderms in Literature 110 How I Began Studying Echinoderms Part 10 Elisa Maldonado 112 Alexandr Yevdokimov ~ 113 Jacob Dafni 113 2 » On the Preservation of Buttlestars by Carla J.
    [Show full text]